[geos-devel] Re: TopologyException makes GEOS/JTS very difficult to employ in my production environments...

G. Allegri giohappy at gmail.com
Wed Sep 29 10:15:38 EDT 2010

Here are the WKB representations of a polygon and a multipolygon which
cause a TopologyException for ST_Difference:

Polygon: http://pastebin.com/rWAGMmME
Multipolygon: http://pastebin.com/sik9jZk2

2010/9/29 G. Allegri <giohappy at gmail.com>:
> Sorry for this strong title, but I would like to open a discussion on
> this topic. There are already several tickets about TopologyException
> happening in various contexts, and I now it is not an easy to solve
> problem. We, in my company, have struggled to circumvent this frequent
> error, and we put some (few) money to let Sandro (strk) analyze it.
> The only solutions, at now, have been various workarounds that (not
> deterministically) work for some cases/datasets, but fail with others.
> Our first "meet" with this exception was due to GeomUnion operations.
> Today we face it for ST_Difference op in PostGIS, and this time no
> workaround is working.
> I anticipate the critics: put the money on the table and someone could
> invest time to solve it. Holy words, this is how foss should work. But
> I'm not the boss of my company, and I've suggested to employ
> PostGIS->GEOS in a big job... and now I have to solve this issue, with
> no extra-money.
>  If this problem cannot be solved I have to abandon PostGIS for one of
> our production environments, and that would be a pity.
> So, my reflection is: in a few weeks we have fighted, almost daily,
> with this error. Are we the only ones to get stuck in it? Have others
> found consistent,deterministic solutions?
> I would be gratefull if you can share your experience and thoughts...
> Giovanni

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